Fuchs' endothelial corneal dystrophy (FECD) affects nearly 4% of the U.S. population over 40 years of age and may cause corneal edema with decreased vision and pain. FECD is the leading indication for corneal transplantation in the country. Genetic variants in COL8A2, SLC4A11, and TCF8 have been linked to FECD but account for only a small fraction of cases. A recent GWAS study found an association between SNPs spanning a 1 Mb region of chr 18q including TCF4/FLJ45743 and late-onset FECD, but the underlying causal variant remains elusive. With CTSA and departmental funds, we have built a large repository of genomic DNA from well-phenotyped patients with corneal disorders including over 250 FECD cases. Our research team has recently begun to apply genetics and genomics-based approaches to investigate the molecular basis of FECD. We have performed genome-wide linkage analysis and have initiated next-generation sequencing on a three generation, Texas family from our cohort with bilineal inheritance of late-onset FECD that segregates as an autosomal dominant trait. Linkage analysis revealed promising intervals on chr 15q (LOD score of 3.93) and chr 1p (LOD score of 2.29). We hypothesize that two disease predisposing genes, one for each lineage, segregate in this unique, inter-married family and when they are co-inherited cause an early-onset, severe FECD. We now propose to: Identify the causal variant(s) underlying an autosomal dominant form of FECD. We will apply next-generation sequencing to the genomic intervals linked to FECD, determine which potential disease causing variants co-segregate with the FECD phenotype in our large pedigree, screen potential pathogenic variants in a cohort of unrelated FECD subjects, and finally assess these novel FECD mutations in a population sample.